How does hair particle friction work?
[![my result][1]][1]

1)The hairs can do hair self collisions only in the same hair particle system! In your example you have two hair systems

2)Internal friction has to be set to 0.2 - 0.8 range.

3) density target slider controls collision margin smaller values equal smaller collision distance. Be careful ! values set too low will cause hair explosions.

4)Strength value (ALWAYS) has to be set to ((1)) unless you want interesting hair strands.

5) Voxel grid cell size optimal value 0.040 

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